Tropical cyclone Sandy revved back up to hurricane strength yesterday as it churned toward the US northeast coast, where it threatens to become one of the worst storms in decades.

The late-season storm has been dubbed 'Frankenstorm' by some weather watchers because it will combine elements of a tropical cyclone and a winter storm and is forecast to reach the US coast close to Halloween.

Forecast models show that it will have all the ingredients to morph into a so-called 'super storm'.

Governors in states along the US east coast have declared emergencies, with officials urging residents to stock up on food, water and batteries.

The US Navy ordered all ships in the Norfolk, Virginia, area, including a nuclear- powered aircraft carrier, out to sea to ride out the approaching storm.

"We're expecting a large, large storm," said Louis Uccellini, director of the National Oceanic and Atmospheric Administration's Centre for Environmental Prediction. He added: "The circulation of this storm as it approaches the coast could cover about the eastern third of the United States."

Sandy battered the Bahamas, south-east of Florida, on Friday after causing widespread destruction in eastern Cuba a day earlier.

The storm was expected to crawl northward yesterday and today and then turn toward the US coast.

Sandy's powerful winds and rains were blamed for 41 deaths in several Caribbean countries, including 11 in Cuba. Most were killed by falling trees and building collapses.